diff options
Diffstat (limited to 'target/s390x/kvm.c')
| -rw-r--r-- | target/s390x/kvm.c | 43 |
1 files changed, 40 insertions, 3 deletions
diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c index 25367807f4..5ec050cf89 100644 --- a/target/s390x/kvm.c +++ b/target/s390x/kvm.c @@ -1867,6 +1867,40 @@ static void unmanageable_intercept(S390CPU *cpu, const char *str, int pswoffset) qemu_system_guest_panicked(NULL); } +/* try to detect pgm check loops */ +static int handle_oper_loop(S390CPU *cpu, struct kvm_run *run) +{ + CPUState *cs = CPU(cpu); + PSW oldpsw, newpsw; + + cpu_synchronize_state(cs); + newpsw.mask = ldq_phys(cs->as, cpu->env.psa + + offsetof(LowCore, program_new_psw)); + newpsw.addr = ldq_phys(cs->as, cpu->env.psa + + offsetof(LowCore, program_new_psw) + 8); + oldpsw.mask = run->psw_mask; + oldpsw.addr = run->psw_addr; + /* + * Avoid endless loops of operation exceptions, if the pgm new + * PSW will cause a new operation exception. + * The heuristic checks if the pgm new psw is within 6 bytes before + * the faulting psw address (with same DAT, AS settings) and the + * new psw is not a wait psw and the fault was not triggered by + * problem state. In that case go into crashed state. + */ + + if (oldpsw.addr - newpsw.addr <= 6 && + !(newpsw.mask & PSW_MASK_WAIT) && + !(oldpsw.mask & PSW_MASK_PSTATE) && + (newpsw.mask & PSW_MASK_ASC) == (oldpsw.mask & PSW_MASK_ASC) && + (newpsw.mask & PSW_MASK_DAT) == (oldpsw.mask & PSW_MASK_DAT)) { + unmanageable_intercept(cpu, "operation exception loop", + offsetof(LowCore, program_new_psw)); + return EXCP_HALTED; + } + return 0; +} + static int handle_intercept(S390CPU *cpu) { CPUState *cs = CPU(cpu); @@ -1914,11 +1948,14 @@ static int handle_intercept(S390CPU *cpu) r = EXCP_HALTED; break; case ICPT_OPEREXC: - /* currently only instr 0x0000 after enabled via capability */ + /* check for break points */ r = handle_sw_breakpoint(cpu, run); if (r == -ENOENT) { - enter_pgmcheck(cpu, PGM_OPERATION); - r = 0; + /* Then check for potential pgm check loops */ + r = handle_oper_loop(cpu, run); + if (r == 0) { + enter_pgmcheck(cpu, PGM_OPERATION); + } } break; case ICPT_SOFT_INTERCEPT: |